Polymer covered vaso-occlusive devices and methods of producing such devices

ABSTRACT

This is a medical device for forming an embolism within the vasculature of a patient. More particularly, it concerns an occlusion device comprising an inner core covered with a polymer. The medical device encourages cellular attachment and growth while maintaining favorable handling, deployment and visualization characteristics.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.11/089,829, filed Mar. 24, 2005, which is a continuation of applicationSer. No. 10/139,096, filed May 3, 2002, now abandoned, which is acontinuation of application Ser. No. 09/874,181, filed Jun. 4, 2001, nowabandoned, which is a continuation of application Ser. No. 09/326,188,filed Jun. 4, 1999, now U.S. Pat. No. 6,280,457.

FIELD OF THE INVENTION

This invention relates to a medical device for forming an embolismwithin the vasculature of a patient. More particularly, it concerns anocclusion device comprising an inner core covered with a polymer. Thedevice encourages cellular attachment and growth while maintainingfavorable handling, deployment and visualization characteristics.

BACKGROUND

Vaso-occlusive devices are surgical implements that are placed withinopen sites in the vasculature of the human body. The devices areintroduced typically via a catheter to the site within the vasculaturethat is to be closed. That site may be within the lumen of a bloodvessel or perhaps within an aneurysm stemming from a blood vessel.

There are a variety of materials and devices which have been used tocreate such emboli. For instance, injectable fluids such asmicrofibrillar collagen, various polymeric foams and beads have alsobeen used. Polymeric resins, particularly cyanoacrylate resins, havebeen used as injectable vaso-occlusive materials. Both the injectablegel and resin materials are typically mixed with a radio-opaque materialto allow accurate siting of the resulted material. There are significantrisks involved in use of a cyanoacrylates, because of the potential formisplacement. Such a misplacement would create emboli in undesiredareas. Cyanoacrylate resins or glues are somewhat difficult, if notimpossible, to retrieve once they are improperly placed.

Other available vaso-occlusive devices include mechanical vaso-occlusivedevices. Examples of such devices are helically wound coils, ribbons andbraids. Various shaped coils have been described. For example, U.S. Pat.No. 5,624,461 to Mariant describes a three-dimensional in-fillingvaso-occlusive coil. U.S. Pat. No. 5,639,277 to Mariant et al. describeembolic coils having twisted helical shapes and U.S. Pat. No. 5,649,949to Wallace et al. describes variable cross-section conicalvaso-occlusive coils. A random shape is described, as well. U.S. Pat.No. 5,645,082 to Sung et al., describes methods for treating arrhythmiausing coils which assume random configurations upon deployment from acatheter. U.S. Pat. No. 5,527,338 to Purdy describes a multi-elementintravascular occlusion device in which shaped coils may be employed.Substantially spherical shaped occlusive devices are described in U.S.Pat. No. 5,423,829 to Pham and Doan. U.S. Pat. No. 5,690,666 entitled“Ultrasoft Embolization Coils with Fluid-Like Properties” by Berensteinet al., describes a coil having little or no shape after introductioninto the vascular space.

There are a variety of ways of discharging shaped coils and linear coilsinto the human vasculature. In addition to those patents which suggestthe physical pushing of a coil out into the vasculature (e.g., U.S. Pat.No. 4,994,069 to Ritchart et al.), there are a number of other ways torelease the coil at a specifically chosen time and site. U.S. Pat. No.5,354,295 and its parent, U.S. Pat. No. 5,122,136, both to Guglielmi etal., describe an electrolytically detachable embolic device.

A variety of mechanically detachable devices are also known. Forinstance, U.S. Pat. No. 5,234,437, to Sepetka, shows a method ofunscrewing a helically wound coil from a pusher having interlockingsurfaces. U.S. Pat. No. 5,250,071, to Palermo, shows an embolic coilassembly using interlocking clasps mounted both on the pusher and on theembolic coil. U.S. Pat. No. 5,261,916, to Engelson, shows a detachablepusher-vaso-occlusive coil assembly having an interlocking ball andkeyway-type coupling. U.S. Pat. No. 5,304,195, to Twyford et al., showsa pusher-vaso-occlusive coil assembly having an affixed, proximallyextending wire carrying a ball on its proximal end and a pusher having asimilar end. The two ends are interlocked and disengage when expelledfrom the distal tip of the catheter. U.S. Pat. No. 5,312,415, toPalermo, also shows a method for discharging numerous coils from asingle pusher by use of a guidewire which has a section capable ofinterconnecting with the interior of the helically wound coil. U.S. Pat.No. 5,350,397, to Palermo et al., shows a pusher having a throat at itsdistal end and a pusher through its axis. The pusher sheath will holdonto the end of an embolic coil and will then be released upon pushingthe axially placed pusher wire against the member found on the proximalend of the vaso-occlusive coil.

In addition, several patents describe deployable vaso-occlusive devicesthat have added materials designed to increase their thrombogenicity.For example, fibered vaso-occlusive devices have been described at avariety of patents assigned to Target Therapeutics, Inc., of Fremont,Calif. Such vaso-occlusive coils having attached fibers is shown in U.S.Pat. Nos. 5,226,911 and 5,304,194, both to Ghee et al. Anothervaso-occlusive coil having attached fibrous materials is found in U.S.Pat. No. 5,382,259, to Phelps et al. The Phelps et al. patent describesa vaso-occlusive coil which is covered with a polymeric fibrous braid onits exterior surface.

In other attempts to increase thrombogenesis, vaso-occlusive coils havealso been treated with variety of substances. For instance, U.S. Pat.No. 4,994,069, to Ritchart et al., describes a vaso-occlusive coil thatassumes a linear helical configuration when stretched and a folded,convoluted configuration when relaxed. The stretched condition is usedin placing the coil at the desired site (by its passage through thecatheter) and the coil assumes a relaxed configuration—which is bettersuited to occlude the vessel—once the device is so placed. Ritchart etal. describes a variety of shapes. The secondary shapes of the disclosedcoils include “flower” shapes and double vortices. The coils may becoated with agarose, collagen or sugar.

U.S. Pat. No. 5,669,931 to Kupiecki et al. discloses coils that may befiled or coated with thrombotic or medicinal material. U.S. Pat. No.5,749,894 to Engleson discloses an aneurysm closure method whichinvolves a reformable polymer.

U.S. Pat. No. 5,536,274 to Neuss shows a spiral implant which may assumea variety of secondary shapes. Some complex shapes can be formed byinterconnecting two or more of the spiral-shaped implants. To promoteblood coagulation, the implants may be coated with metal particles,silicone, PTFE, rubber lattices, or polymers.

None of the documents described above suggest a device such as thatclaimed herein.

SUMMARY OF THE INVENTION

This invention relates to devices and to methods for makingvaso-occlusive devices typically at least partially covered by apolymeric fiber. The vaso-occlusive device often will have a primaryshape of a helical coil. In particular, one variation of the inventivedevice is a simple wire wrapped with at least one polymeric fiber. Theterm polymeric fiber used throughout this invention, refers to, forexample, a mono-filament, such as a single filament, or a multi-filamentconstruction, such as a plurality of single filaments wound, braided, orotherwise joined together. The wire is then formed into a primary shapeof a helical coil. The helical coil may be, for example, elongated orsubstantially spherical. Also, the pitch of the polymeric fiber on thewire may range from, for example, open to closed, depending upon thedesired density of polymer desired. The pitch of the fiber may also beconsistent or vary along the wire.

Another variation of the inventive device is a wire formed into aprimary shape of a helical coil with at least one polymeric fiber thatis wound or braided about the helical coil, thus covering the coil. Thehelical coil may be, for example, elongated or substantially spherical.Also, the pitch of the polymeric fiber on the coil may range from, forexample, open to closed, depending upon the desired distal density ofpolymer desired. For example, a fiber with an open pitch will havespaces between each turn of the fiber, while a fiber with a closed pitchwill not have spaces between each turn. The proximal pitch of thepolymeric fiber may also be consistent or vary along the coil.

Another variation of the inventive device is at least one polymericfiber braided about the device. The braid covering the device may bewoven with or without openings. In the case where the braid is wovenwithout openings, the braid may be, for example, tightly braided.

Another variation of the inventive device is a polymer coveredvaso-occlusive device having a primary shape substantially of a helicalcoil and further having a secondary shape. This secondary shape of thepolymer covered device may be selected from a variety of shapes andsizes tailored for the particular use of the inventive vaso-occlusiondevice. Such secondary shapes are, for example, a clover-leaf, figure-8,substantially spherical, flower-shaped, vortex, ovoid, randomly shaped.The random shape includes both randomly shaped 2-D and 3-D coils. Othershapes as required for a particular use of the invention are also withinthe scope of this invention.

An aspect of this inventive device is that the vaso-occlusive device maybe radiopaque, e.g., a radiopaque inner core wire or the addition of aradiopaque additive added to the polymeric fiber. The device may alsoemploy a detachable tip, e.g., mechanically detachable, electrolyticallydetachable, etc. Yet another variation of the invention is the use of aninsulative or highly resistive member proximally of the coil. Theresistive or insulating member may be any suitable material such asinorganic oxides, glues, polymeric inserts, polymeric coverings, etc.This insulative or highly resistive layer or joint appears to focus thecurrent flow through the sacrificial electrolytic joint and therebyimproves the rate at which detachment of the implant occurs.

The polymeric material of the inventive device may be, but is notlimited to, protein based polymers, absorbable polymers, and non-proteinbased polymers, or a combination thereof. The wire may be, but is notlimited to gold, rhenium, platinum, palladium, rhodium, ruthenium,stainless steel, tungsten, and alloys thereof, or any combinationthereof.

The polymeric material may be a carrier for various agents, for example,drugs, medicines, growth factors, or genes.

Another variation of this invention includes coils having at least onestretch-resisting member extending through the interior of the primaryshape of the coil. The stretch resistant member is fixedly attached,directly or indirectly, to the coil in at least two locations. Thestretch-resisting member is preferably loose within the coil to preventbinding of the coil during passage of the coil through turns in thevasculature. A stretch-resisting member may also be used in a coil witha secondary shape.

This invention further includes the process of winding or braiding atleast one polymeric fiber about a wire and shaping the covered wire intoa primary shape of, for example, a helical coil. Again, the polymericfiber includes, for example, a mono-filament, such as a single filament,or a multi-filament construction, such as a plurality of filamentswound, braided, or otherwise associated or joined together. As mentionedabove, the pitch of the polymeric fiber may range, for example, fromopen to closed, or the pitch may vary, depending upon the desireddensity of polymer wanted on the final device.

Another process variation of the invention includes the steps of windingor braiding at least one polymeric fiber about a mandrel, for example, aTeflon mandrel, then applying heat to the polymeric fiber. Next, theheated polymeric fiber is removed from the mandrel and attached to the awire having a primary shape of, for example, a helical coil.

The invention may include, for example, dipping or extruding a polymericmaterial upon the wire and then shaping the wire into a primary shape.

The invention may also include the step of further shaping a polymericcovered wire having a primary shape into a secondary shape. This may beperformed, for example, by pulling a stylet through the primary shape ofthe polymeric covered wire. Examples of such secondary shapes areprovided above.

This invention may also includes the step of further heating a polymericcovered wire after the polymeric covered wire is shaped into a secondaryshape.

This invention further includes the process of at least partiallyoccluding an aneurysm using the inventive vaso-occlusive device asdescribed above. For, example, the device may be deployed into theaneurysm by using a detachable tip. As described above, the detachabletip may be, for example, an electrolytically detachable or mechanicallydetachable tip.

As will become apparent, preferred features and characteristics of onevariation and/or aspect of the invention are applicable to any othervariation and/or aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a partial view of a polymeric covered occlusive devicehaving a core wire having a primary shape with at least one polymericfiber wrapped about the core wire

FIG. 1B shows a partial sectional view of a polymeric covered occlusivedevice having a core wire having a primary shape with at least one woundpolymeric fiber covering the primary shape of the device.

FIG. 1C shows a side view, partial cutaway of a vaso-occlusive coil madeaccording to the invention having a generally linear fibrousstretch-resisting member.

FIG. 1D shows a side view, partial cutaway of a vaso-occlusive coil madeaccording to the invention having a generally linear wirestretch-resisting member.

FIG. 1E shows a side view, partial cutaway of a vaso-occlusive coil madeaccording to the invention having a generally helical stretch-resistingmember.

FIGS. 1F, 1G, and 1H show side view, partial cutaways of typical ends ofthe inventive vaso-occlusive coils.

FIGS. 2A-2G illustrate variations of a polymeric covered occlusiondevice having secondary shapes.

FIG. 2A illustrates a variation of a polymeric covered occlusion devicehaving a secondary shape of that of a clover leaf.

FIG. 2B illustrates a variation of a polymeric covered occlusion devicehaving a secondary shape of that of a twisted figure-8.

FIG. 2C illustrates a variation of a polymeric covered occlusion devicehaving a secondary shape of that of a flower.

FIG. 2D illustrates a variation of a polymeric covered occlusion devicehaving a substantially spherical secondary shape.

FIG. 2E illustrates a variation of a polymeric covered occlusion devicehaving a random secondary shape.

FIG. 2F illustrates a variation of a polymeric covered occlusion devicehaving a secondary shape of that of a vortex.

FIG. 2G illustrates a variation of a polymeric covered occlusion devicehaving an secondary shape of that of an ovoid.

FIG. 3 illustrates the method of winding or braiding at least onepolymeric fiber about a wire.

FIG. 4 illustrates a method of shaping a secondary shape by pulling astylet through a primary shape of a polymeric wrapped wire.

FIG. 5A illustrates a method of deploying a polymeric covered occlusiondevice to at least partially occlude an aneurysm.

FIG. 5B illustrates a polymeric covered occlusion device with anmechanically detachable tip.

FIG. 5C illustrates a polymeric covered occlusion device with aelectrolytically detachable tip.

FIG. 5D illustrates a polymeric covered occlusion device with aelectrolytically detachable tip with a highly resistive or insulativemember proximally of the implant.

DESCRIPTION OF THE INVENTION

This invention involves vaso-occlusive devices which are at leastpartially wrapped with polymeric fiber and methods of producing thosevaso-occlusive devices.

FIG. 1A shows a typical vaso-occlusive device (100) in which a wire(104) has been wrapped with a polymer (102) according to the proceduresdescribed herein. Vaso-occlusive device (100) is shown in FIG. 1 A tocomprise a primary shape of a helically wound coil (104) having tips(106) to ease the potential of the component wire to cause trauma in ablood vessel. The device is made up of a wire (104) which has beenwrapped with a polymeric fiber (102). In the illustration of FIG. 1A,the fiber (102) is wrapped about the wire (104) with an open pitch.However, a closed pitch (not shown) is also contemplated. In thisvariation, the polymeric fiber (108) is displayed as a single filament.However, a multi-filament (not shown), such as a plurality of filamentsjoined together is also contemplated. The polymeric fiber (108) may beattached to the wire (110) at any (or all) points on the wire (110).Obviously, the polymeric fiber is first placed on the wire per se andthe combination of fiber and wire is then made into the primary shape,i.e., the helical coil, using one of the procedures described below.

FIG. 1B shows another variation of the vaso-occlusive device (100) inwhich a polymeric fiber (108) has been placed over a helically woundcoil (104) which has already been formed into its primary shape. In thisexample, the primary shape of the device (100) is a helically woundcoil. The device (100) has tips (106) to minimize the potential of thecomponent wire to cause trauma in a blood vessel. Again, the pitch ofthe fiber (108) about the device (100) is shown to be closed forillustrative purposes only, it is also contemplated that the pitch maybe open.

Preferably, the device (100), which may have a primary shape of ahelical coil as shown in the Figures, comprises a radio-opaque,biocompatible material such as a metal or a polymer. The device (100)may be, but is not necessarily, subjected to a heating step to set thewire into the primary shape. Suitable metals may be selected from gold,rhenium, platinum, palladium, rhodium, ruthenium, various stainlesssteels, tungsten, and alloys thereof. The preferred alloy is onecomprising upwards of 90 percent platinum and at least a portion of theremainder, tungsten. This alloy exhibits excellent biocompatibility andyet has sufficient strength and ductility to be wound into coils ofprimary and secondary shape and will retain those shapes upon placementof the vaso-occlusive device in the human body. The diameter of the wiretypically making up the coils is often in a range of 0.005 and 0.050inches, preferably between about 0.001 and about 0.003 inches indiameter.

The polymeric material (106, 108) covering the device may be selectedfrom a wide variety of materials. On such example is a suture-typematerial which is for example, a single mono-filament or multiplefilaments braided or otherwise associated or joined together. Syntheticand natural polymers, such as polyurethanes (including block copolymerswith soft segments containing esters, ethers and carbonates),polyethers, polyimides (including both thermosetting and thermoplasticmaterials), acrylates (including cyanoacrylates), epoxy adhesivematerials (two part or one part epoxy-amine materials), olefins(including polymers and copolymers of ethylene, propylene butadiene,styrene, and thermoplastic olefin elastomers), polydimethylsiloxane-based polymers, cross-linked polymers, non-cross linkedpolymers, Rayon, cellulose, cellulose derivatives such nitrocellulose,natural rubbers, polyesters such as lactides, glycolides, caprolactonepolymers and their copolymers, hydroxybutyrate and polyhydroxyvalerateand their copolymers, polyether esters such as polydioxinone, anhydridessuch as polymers and copolymers of sebacic acid, hexadecandioic acid andother diacids, orthoesters may be used. Mixtures, copolymers (both blockand random) of these materials are also suitable. Polyethyleneteraphthalate (PET or Dacron) is a preferred non-biodegradable polymer.In a preferred variation, the polymeric fiber comprises materials whichare biodegradable and that have already been approved for use in woundhealing in humans. Typically and preferred biodegradable polymersinclude polyglycolic and polylactic acids.

The pitch of the winding of the polymeric fiber (102, 108) can rangefrom closed to open depending on the desired density of polymer. Theresulting primary coil diameter typically is in the range of 0.005 to0.150 preferably 0.008 and 0.085 inches. Smaller coil diameters are usedfor finer problems and larger coil diameters and wire diameters are usedin larger openings in the human body. A typical coil primary diameter is0.007 and 0.018 inches. The axial length of a vaso-occlusive device maybe between 0.5 and 100 centimeters. The coils are typically wound tohave between 10 and 75 turns per centimeter.

In the variation detailed in FIG. 1A, at least one polymeric fiber (102)is first wound over a wire (104). While this variation discusses windingthe fiber (102) over the wire (104), the invention includes the act ofbraiding the fiber (102) about the wire (104) as well. The polymer tendsto flatten onto the wire, taking on a low profile and the appearance ofa ribbon. The covered wire is then formed into a primary shape, forexample a coil, by winding the primary shape about a cylindrical orconical mandrel. Other suitable primary shapes include braids, ribbonsor the like. Preferably, the primary shape is formed by using a closedpitch winding over a mandrel diameter of between about 0.005 and about0.009 inches. Larger or smaller mandrels and open pitches may also beemployed. The occlusion devices of the invention may be made usingconventional equipment and procedures.

The polymer may be made to adhere to the underlying wire by melting thepolymer or by the use of adhesives or by other suitable means. Thethen-secured polymer covered wire is then rolled into a helical shape.

FIG. 1B depicts a typical vaso-occlusive device (100) in which a wire(104) has been formed into the primary shape of a helical coil. Thehelical coil is then covered with a wrapped polymeric fiber (108) usingthe procedures described below. Vaso-occlusive device (100), as shown inFIG. 1B, comprises a helically wound coil having tips (106) to ease thepotential of the component wire to cause trauma in a blood vessel. Thedevice comprises a wire (104) wrapped in a closed pitch fashion with apolymeric fiber (108). Heat may be applied to the wrapped polymericfiber prior to the placement of the fiber (108) on the wire (104) orsubsequent to the placement of the fiber on the coiled wire (104) toprovide some form to the polymeric fiber.

FIGS. 1C, 1D, and 1E show side-view partial cross-sections of variationsof the inventive coil with stretch-resistant members. In theseillustrations, the polymeric covering (108) is shown to be wrapped aboutthe primary shape (104) for illustrative purposes only. The use of awire wrapped with at least one polymeric fiber (not shown) is alsocontemplated with these variations of the inventive device.

The variations shown in FIGS. 1C and 1D are made up of a helically woundouter coil (104) having a first end (106, 112) and a second end (110,114). These variations include a stretch-resisting member (116, 118)which is shown to be fixedly attached both to the first end (106, 112)and to the second end (110, 114). In certain circumstances, it may bedesirable to attach the stretch-resisting member (116, 118) only to oneof the two ends, to at least one site between the to ends, or to neitherof the two ends. Clearly, for attaining stretch resistance, thestretch-resisting member must be attached to at least two points on thecoil.

The stretch-resisting member (116) of the variation shown in FIG. 1C isfibrous and desirably polymeric. The stretch-resisting member (116) maybe thermoplastic or thermosetting and comprise a bundle of strands or asingle strand melted onto, glued, or otherwise fixedly attached to thevaso-occlusive coil (100).

In this variation of the invention, the stretch-resisting member ispreferably a polymer (natural or synthetic) which may be heat-set in thesecondary form in situ. The use of heat-treated or heat-formed polymericstrand (single or multiple) should not affect the secondary shape of thecoil and provides stretch resistance while allowing the selected form ofthe device to perform its occlusive function without interference fromthe safety component. In some instances, it may also be desirable toinclude one or more metallic strands in the stretch-resisting member(116) to provide stiffness or electrical conductance for specificapplications.

The stretch-resisting member (118) of the variation shown in FIG. 1D isa simple wire or “ribbon” which is soldered, brazed, glued, or otherwisefixedly attached to the first end (106), second end (110), or to thecoil at one or more locations intermediate to those the ends.

The variation shown in FIG. 1E includes a stretch-resisting member (120)which is comprised of a helically wound coil which is soldered, brazed,glued, or otherwise fixedly attached to the first end (106) or secondend (110) or in one or more intermediate locations. Thestretch-resisting member (120) in this configuration provides a greatermeasure of lateral flexibility than the wire variation (118 in FIG. 1D).It may be wound in either the same direction as is the outer coil (104)or in the alternate direction. A modest drawback to this variation isthat it will stretch more than the FIG. 1D variation when axiallystressed.

The materials used in constructing the stretch-resisting member (116,118, 120) may be any of a wide variety of materials; preferably, aradio-opaque material such as a metal or a polymer is used. Suitablemetals and alloys the stretch-resisting member (116, 118, 120) includethe Platinum Group metals, especially platinum, rhodium, palladium,rhenium, as well as tungsten, gold, silver, tantalum, and alloys ofthese metals. These metals have significant radio-opacity and in theiralloys may be tailored to accomplish an appropriate blend of flexibilityand stiffness. They are also largely biologically inert. Highlypreferred is a platinum/tungsten alloy, e.g., 8% tungsten and theremainder platinum.

In some variations of the invention, the ribbon or coilstretch-resisting members (116, 118, 120) may be of any of a widevariety of stainless steels if some sacrifice of radio-opacity andflexibility may be tolerated. Very desirable materials of construction,from a mechanical point of view, are materials which maintain theirshape despite being subjected to high stress. Certain “super-elasticalloys” include various nickel/titanium alloys (48-58 atomic % nickeland optionally containing modest amounts of iron); copper/zinc alloys(38-42 weight % zinc); copper/zinc alloys containing 1-10 weight % ofberyllium, silicon, tin, aluminum, or gallium; or nickel/aluminum alloys(36-38 atomic % aluminum). Particularly preferred are the alloysdescribed in U.S. Pat. Nos. 3,174,851; 3,351,463; and 3,753,700.Especially preferred is the titanium/nickel alloy known as “nitinol”.These are very sturdy alloys which will tolerate significant flexingwithout deformation even when used as very small diameter wire.

If a super-elastic alloy such as nitinol is used in the device, thediameter of the coil wire may be significantly smaller than that usedwhen the relatively more ductile platinum or platinum/tungsten alloy isused as the material of construction.

Once the primary coil (104) is wound, the stretch-resisting member (116,118, 120) is inserted into the lumen of the primary coil (104) andsecured to the coil as desired. Ends (106, 112, 110, 114) are preferablyof the same diameter as is the primary coil (104).

Alternatively, the primary coil is shaped into its secondary form, andheat treated so that the coil will return to the secondary form whenrelaxed. The stretch-resistant member is then inserted into the lumen ofthe coil and secured as desired. The stretch-resisting member does notsubstantially affect the shape of the coil when the coil returns to thesecondary form. Preferably, the stretch-resistant member is attached toa hook inside the lumen and heat treatment used to fuse at least partsof the polymer to the coil. The coil is then allowed to relax to formits secondary form and any stretch-resistant filaments extending fromthe coil are heat sealed to the coil. It is required that there be someamount of slack in the polymer to allow the coil to pass through thecatheter as described herein and to allow the coil to return to itssecondary form. The secondary coil may be heated treated. Preferably,heat treatment occurs at a temperature from at least about the T_(g) ofthe polymer to a temperature below the melting point of polymer.

Suitable polymeric materials for the polymeric stretch-resisting member(116, 118, 120) can be either thermosetting or thermoplastic. For thisvariation of the invention, however, the polymer should be one for whicha strand may be heat-treated to accept a form corresponding to thesecondary form. Thermoplastics are preferred because they allowsimplification of the procedure for constructing the device (100) sincethey may be melted and formed into the end or ends (106, 112, 110, 114).Simple devices such as soldering irons may be used to form the ends.Thermosetting plastics would typically be held in place by an adhesive.Suitable polymers include most biocompatible materials which may be madeinto fibers but include thermoplastics, e.g., polyesters such aspolyethyleneterephthalate (PET) especially Dacron; polyamides includingthe Nylons; polyolefins such as polyethylene, polypropylene,polybutylene, their mixtures, alloys, block and random copolymers;polyglycolic acid; polylactic acid; fluoropolymers(polytetrafluoro-ethylene), or even silk or collagen. Thestretch-resistant polymer may be made from materials used as dissolvablesutures, for instance polylactic acid or polyglycolic acid, to encouragecell growth in the aneurysm after their introduction. Preferred becauseof the long history of safe and effective usage in the human body arefibrous PET (sold as Dacron) and polypropylene. Highly preferred ispolypropylene, for instance, in the form of 10-0 and 9-0 polypropylenesuture material. We have found that the diameter of the polymer istypically between about 0.0001 inches and about 0.01 inches.

FIGS. 1F, 1G, and 1H show side-view partial cross-sections of an end ofinventive coil (100). Again, in these illustrations, the polymericcovering (108) is shown to be wrapped about the primary shape (104) forillustrative purposes only. The use of a wire wrapped with at least onepolymeric fiber (not shown) is also contemplated with these variationsof the inventive device. FIG. 1F also shows the helically wound outercoil (104) having an end (110) which is formed from a formerly moltenstrand which also makes up the stretch-resisting member (116). An end ofthis type may be considered to have modestly higher vaso-occludingproperties than a metallic end. Other functional equivalents to thisstructure include ends (110) formed of glues such as epoxies and theirequivalents, and which are mechanical in nature.

FIG. 1G shows an external knot (122) which fixes the length of the coilmember (104) and keeps it from stretching; FIG. 1H shows a reformed massof formerly molten polymer or of glue which is of a diameter larger thanthe inner diameter of coil (104) and prevents the coil from stretching.The knot (122) and block (124) are not shown to be attached to the coil(104) but may be.

The vaso-occlusive devices shown are illustrative of the coils describedbelow.

FIG. 2A-2G illustrates a vaso-occlusive device (100) of this inventionhaving a secondary shape. These shapes are simply indicative of thevarious secondary shapes suitable for this invention. Other shapes maybe used as well. While not shown, the devices illustrated in FIGS. 2A-2Gincorporate the polymeric fiber as provided in FIGS. 1A-1B. The device(100) may be, but is not necessarily, subjected to a heating step asknown to one skilled in the art to set the device into a secondaryshape. As previously mentioned, the devices (100) having secondaryshapes, may, but are not limited to including a stretch resistingmember.

FIG. 2A depicts a device (100) having a secondary shape of a cloverleaf. FIG. 2B depicts a device (100) having a secondary shape of atwisted figure-8. FIG. 2C depicts a device (100) having a flower-shapedsecondary shape. FIG. 2D depicts a device (100) having a substantiallyspherical secondary shape. FIG. 2E illustrates a device (100) having arandom secondary shape. FIG. 2F illustrates a device (100) havingsecondary shape of a vortex. FIG. 2G illustrates a device (100) having asecondary shape of an ovoid.

FIG. 3 illustrates, the method of wrapping at least one polymeric fiber(102) about a wire (104) which is subsequently formed into a primaryshape (not shown.) The wire (104) is rotated and the polymeric fiber(102) is simply wound onto the rotating wire. As mentioned above, thepitch of the fiber (102) may be either open or closed. The polymericfiber (102) may be made to adhere to the wire (104) at one or moreplaces. The fiber (102) itself may be sticky by, e.g., addition of suchadhesives as ethylvinylacetate (EVA) to the polymer or onto the fiberitself.

FIG. 4 depicts a method of forming a secondary shape from the primarypolymer covered shape. A stylet, mandrel, or shaping element (200)having a specific tip shape (210) is pulled through the inner diameterof the device (100), thereby mechanically working and shaping the device(100). In some instances, the mandrel may be used along with heat toshape the device.

Not shown is the step of further heating a polymeric covered deviceafter the device is formed into a secondary shape. This additionalheating step may be used to set the polymeric material to the secondaryshape of device (100).

FIG. 5A illustrates the deployment of the device (100) into an aneurysm(220). In this instance, the device (100) is placed in the aneurysm(220) with the aid of a catheter (222). The catheter (222) is maneuveredto the neck (224) of the aneurysm (220). In this example, the device(100) has a random secondary shape, however, the device (100) may haveany shape as the situation requires.

FIG. 5B illustrates a variation of a device (100) having a mechanicallydetachable tip (300). The device is deployed using a delivery device(304) e.g., a catheter, and a pusher (306) having a mechanicallydetachable tip (302). When the delivery device (304) is withdrawn, themore proximal mechanically detachable tip (302) is able to separate fromthe mechanically detachable tip (300) lodged on the coil (100).

FIG. 5C illustrates a variation of a device (100) having anelectrolytically detachable tip (314). The device (100) is delivered viaa pusher (308) having an electrolytically detachable tip (312). Thedevice (100) is connected to the pusher (308) via an electrolyticallydetachable joint (310). When the device (100) is placed as desired inthe aneurysm (220), the electrolytically detachable joint (310) isdissolved via applying an appropriate electrical current to the pusher(308). The Guglielmi patent described above provides an expandedexplanation of how the electrolytically severable joint operates.

FIG. 5D illustrates a variation of the electrolytic joint with aninsulative layer. FIG. 5D shows a close-up of the more distal portion ofone variation of the invention. This variation includes the core wire(310) and the attached implant (320). Typically, core wire (310) will beconductive but covered with a insulative layer (311) both proximal anddistal of electrolytically severable joint (312). The interior of corewire (310) is physically attached to implant (320). In this variation ofthe invention, implant (320) is a helically wound coil.

In this variation, a highly resistive or insulative layer or memberelectrically isolates implant (320) from core wire (310). In thisvariation of the invention, the insulating layer (311) on the core wire(310) is simply continued to the end of the core wire (310). An optionalbushing (314) is placed on the core wire (310) to further separate itfrom implant (320). Optional bushing (314) may be of any suitablematerial since it operates merely as a spacer. Insulating layer (311)may be polytetrafluoroethylene (e.g., Teflon), polyparaxylxylene (e.g.,Parylene), polyethyleneterephthalate (PET), polybutyleneterephthalate(PBT), cyanoacrylate adhesives, or other suitable insulating layer, butpreferably is polymeric and most preferably is PET.

The devices made according to the procedure of this invention may beintroduced to a selected site within the body using the procedure suchas the one outlined below. This procedure may be used in treating avariety of maladies. For instance, in treatment of an aneurysm (220),the aneurysm (220) itself may be filled with the devices made accordingto the procedure specified here. Shortly after the devices are placedwithin the aneurysm (220), it is thought that the outer coating causesan irritation at the site. An emboli begins to form and, at some latertime, is at least partially replaced by highly vascularized materialwhich is at least partially collagenous. This mass is formed around theinventive vaso-occlusive devices.

In general, a selected site is reached through the vascular system usinga collection of specifically chosen catheters and guide wires. It isclear that should the aneurysm (220) be in a remote site, e.g., in thebrain, methods of reaching this site are somewhat limited. One widelyaccepted procedure is found in U.S. Pat. No. 4,994,069 to Ritchart, etal. It utilizes a fine endovascular catheter such as is found in U.S.Pat. No. 4,739,768, to Engelson.

First of all, a so-called “introducer” catheter is introduced through anentry site in the vasculature. Typically, this would be through afemoral artery in the groin. Other entry sites sometimes chosen arefound in the neck and are in general well known by physicians whopractice this type of medicine. Once the introducer is in place, asmaller but still fairly large catheter, such as a guiding catheter, isthen used to provide a safe passageway from the entry site to a regionnear the site to be treated. For instance, in treating a site in thehuman brain, a guiding catheter would be chosen which would extend fromthe entry site at the femoral artery, up through the large arteriesextending to the heart, around the heart through the aortic arch, anddownstream through one of the arteries extending from the upper side ofthe aorta. The guide catheter would terminate in the region just abovethe neck. A guidewire and neurovascular catheter such as that describedin the Engelson patent are then placed through the guiding catheter as aunit. Once the tip of the guidewire reaches the end of the guidingcatheter, it is then extended using fluoroscopy, by the physician to thesite to be treated. During the trip between the treatment site and theguide catheter tip, the guidewire is advanced for a distance and theneurovascular catheter follows. Once both the distal tip of theneurovascular catheter and the guidewire have reached the treatmentsite, and the distal tip of that catheter is appropriately situated,e.g., within the mouth of an aneurysm (220) to be treated, the guidewireis then withdrawn. The neurovascular catheter then has an open lumen tothe outside of the body. The devices of this invention are then pushedthrough the lumen to the treatment site. They are held in placevariously because of their shape, size, or volume. These concepts aredescribed in the Ritchart et al patent as well as others. Once thevaso-occlusive devices are situated in the vascular site, the embolismforms.

In another variation, the polymeric fiber covering the device are usedas a carrier for bioactive molecules. Non-limiting examples of bioactivematerials which increase cell attachment and/or thrombogenicity includeboth natural and synthetic compounds, e.g., collagen, fibrinogen,vitronectin, other plasma proteins, growth factors (e.g., vascularendothelial growth factor, “vEGF”), synthetic peptides of these andother proteins having attached RGD (arginine-glycine-aspartic acid)residues, generally at one or both termini. In addition, polynucleotidesequences encoding peptides (e.g., genes) involved in wound healing orpromoting cellular attachment may also be used.

Modifications of the procedure and device described above, and themethods of using them in keeping with this invention will be apparent tothose having skill in this mechanical and surgical art. These variationsare intended to be within the scope of the claims that follow.

1. A method of occluding a treatment site within a vascular system,comprising the steps of: introducing a catheter having a proximal endand a distal end into the vascular system; positioning the distal end ofsaid catheter proximate the treatment site; advancing a vaso-occlusivedevice through the catheter and into the treatment site, thevaso-occlusive device comprising a wire having an outer circumferentialsurface and formed into a helically wound primary shape, and at leastone fiber helically wound about and onto the circumferential surface ofsaid wire.
 2. The method of claim 1, wherein said at least one fiber iswound about the wire with a closed pitch.
 3. The method of claim 1,wherein said at least one fiber is wound about the wire with an openpitch.
 4. The method of claim 1, wherein said vaso-occlusive device isradiopaque.
 5. The method of claim 1, wherein said at least one fibercomprises a radiopaque additive.
 6. The method of claim 1, wherein saidvaso-occlusive device further comprises a detachable tip.
 7. The methodof claim 6, wherein said detachable tip is an electrolytically severablejoint attached to the vaso-occlusive device.
 8. The method of claim 1,wherein said at least one fiber is one of a polyether fiber material andan acrylate fiber material.
 9. The method of claim 1, wherein said wirehas a secondary shape different from said helically wound primary shape.10. The method of claim 9, wherein said secondary shape is selected fromthe group consisting of clover-leaf shaped, figure-8 shaped,flower-shaped, vortex-shaped, ovoid, and substantially spherical. 11.The method of claim 9, wherein said vaso-occlusive device furthercomprises a stretch-resisting-member having a first end and a secondend, the stretch-resisting member extending through at least a portionof an interior of said primary shape, said stretch-resisting memberattached to said wire in at least two locations.
 12. The method of claim1, wherein said at least one fiber is absorbable.
 13. The method ofclaim 1, wherein said at least one fiber is formed of a polymermaterial.
 14. The method of claim 1, further comprising the steps of:positioning an introducer catheter into the vasculature; advancing aguiding catheter through said introducer catheter to a site near thetreatment site; and advancing said catheter and a guidewire through saidguiding catheter.
 15. The method of claim 1, wherein the treatment siteis an aneurysm.
 16. The method of claim 15, wherein the aneurysm is aneurovascular aneurysm.
 17. The method of claim 1, wherein the at leastone fiber is helically wound at least one complete turn about thecircumferential surface of said wire.
 18. The method of claim 1, whereinthe at least one fiber is helically wound about substantially all thecircumferential surface of said wire.